1. Field of the Invention
This invention relates to a railroad track ballast tamping device and, more specifically, to a tamping device wherein a vibration motor has a housing with air passages.
2. Background Information
The gravel-like ballast underlying a railroad track must be compressed during the installation of new track or repairing old track. The typical means for compressing the railroad track ballast is to vibrate and/or tamp the ballast using a tamping machine. A tamping machine, which is mounted on a rail vehicle, typically consists of at least two pairs of tamping tools connected to a common vibrating device. Each tamping tool includes an elongated tamping head which is structured to be inserted into the ballast. An individual tamping head may include a fork-like tip with two, or more, prongs. A pair of tamping tools is further structured to move in a pincer-like manner. Typically in a pair of tamping tools, the individual tamping heads are in a spaced relation to each other so that the tamping heads may be inserted into the ballast on either side of a tie. The tamping heads are aligned so that the heads of an associated pair of tamping tools are disposed on one side of a rail. Further, a second pair of tamping tools is, typically, adjacent to the first pair but located on the other side of the rail. Thus, during a tamping operation, at the location of the intersection of a rail and tie, a tamping head will be disposed on each side of the tie and on each side of the rail. The tamping machine further, typically, includes two pairs of tamping tools disposed over each of the two rails in a railroad track.
During the tamping operation, the tamping heads are usually in a generally vertical orientation when inserted into the ballast. The tamping heads of an associated pair of tamping tools are then drawn together in a pincer-like motion so that the tamping heads are generally adjacent to a selected tie. The vibrating device is then actuated causing the tamping heads to vibrate and compress the ballast. The tamping heads are then removed from the ballast and the tamping machine is indexed, that is moved, to the next tie and the operation is repeated.
The vibrating device is coupled to each tamping tool. That is, each tamping tool may have a dedicated, or individual, vibrating device or a vibrating device may be mounted on a cross-member extending between the two or more tamping tools located on one side of a rail. The vibrating device, typically, includes an irregular flywheel that is rotated at high speed. The irregular shape of the flywheel causes the flywheel to vibrate during rotation. The vibration from the flywheel is mechanically transferred to the tamping heads via the tamping tool housing or frame assembly. That is, the flywheel typically rotates about a hub which has an axis of rotation that extends generally parallel to the ties and generally perpendicular to the rails. The hub engages a pair of bearings, one bearing on each side of the flywheel and is coupled to a motor. The flywheel and bearings are disposed within a closed housing assembly. The housing assembly is coupled, and preferably fixed, to the tamping tool frame assembly. The housing assembly is typically sealed. That is, the housing assembly is, essentially, airtight. However, there may be small passages that allow an insignificant amount of air to pass in and out of the housing assembly.
During a tamping operation the rotation of the flywheel creates friction with the bearings. Thus, a lubricant is typically applied to the bearings. The lubricant is structured for normal operations in open spaces and moderate environmental temperatures. While a sealed housing assembly generally provides acceptable performance, it has been noted that in warmer climates or in closed spaces, e.g. a tunnel, heat builds up within the closed housing assembly. When the heat buildup is not relieved, the temperatures within the housing assembly may pass the breakdown point of the lubricant. When the lubricant breaks down, the friction between the moving components cause enhanced wear and tear and, in very rare instances, may cause a complete failure of the vibrating device. Additionally, lubricant formulas are subject to change by various manufacturers. It has been observed that lubricants that have been acceptable in one formulation may be subject to heat related breakdown in a later formulation. Further, even when a lubricant does not fail due to an instance of excessive heat, the high operating temperatures cause the lubricants to wear out more rapidly.